Some vertebrates show hibernation in winter. Birds and mammals do not show this feature. Give reason.

Explanation

### Step-by-Step Solution:

1. **Understanding Hibernation**: Hibernation refers to a state of inactivity and metabolic depression in endotherms (warm-blooded animals) during winter. It is a survival strategy that allows animals to conserve energy when food is scarce and environmental conditions are harsh.

2. **Identifying Hibernating Vertebrates**: Hibernation is commonly observed in certain vertebrates, particularly in ectothermic animals (cold-blooded), such as reptiles and amphibians. These animals can enter a state of dormancy during cold weather.

3. **Metabolic Changes in Ectotherms**: Ectotherms, like lizards and tortoises, do not maintain a constant internal body temperature. Their body temperature fluctuates with the environment. When temperatures drop, their metabolism slows down significantly, allowing them to survive without food for extended periods.

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